Windmill

Windmill turns scripts into workflows and UIs in minutes. Write a Python function, TypeScript handler, or SQL query — Windmill auto-generates a UI, handles scheduling, webhooks, and error handling. It's the open-source lovechild of Retool (internal tools) and Temporal (workflow orchestration), and it benchmarks 13x faster than Airflow.

The breadth of triggers is impressive: schedules, webhooks, HTTP routes, Kafka, WebSockets, email. Supports Python, TypeScript, Go, Bash, SQL, Rust, PowerShell. The web IDE and low-code builders lower the bar for non-engineers. Compared to Retool (commercial, UI-first), Windmill is code-first and free. Compared to Temporal (more powerful workflows), Windmill is more accessible. Compared to n8n (visual automation), Windmill is more developer-oriented.

Use this when you need internal tools and workflow automation without building everything from scratch. Skip this if you only need workflow orchestration — Temporal or Prefect are more focused.

The catch: the "Other" license needs checking — Windmill uses AGPL-3.0 with an enterprise tier. Being a platform means lock-in if you adopt it deeply. And trying to be both Retool and Temporal means it's not the best at either.